The Yellow River Delta has been shrinking by an average of 7.6 square kilometers a year since 1996, according to the Shandong Provincial Bureau of Geology and Mineral Resources.

A report on the delta's coastline stability said that, in contrast to its previous annual increase of 22 square kilometers, the situation has reversed in recent years.

"Silt drifts into the delta with river water," Kang Fengxin, from the bureau's geological research department, told China Daily.

"This has happened particularly on the northern border of the delta in Dongying, where it empties into the Bohai Sea after crossing nine provinces and more than 5,500 kilometers."

As a result of accumulative deposits over centuries, a spectacular delta has formed ten meters above the riverbed in the river's lower reaches. But the silt deposits may be more than offset by erosion, according to experts.

They say seawater currents and an increase in the number of days when this section of the river runs dry are causing greater erosion. Since 1972, the number of dry days has been on the rise, with 226 in 1997 alone.

Site survey and satellite photos taken over the past three decades have testified to the gradual erosion of the delta.

"Countermeasures have to be worked out to address the situation," Kang said, adding that a more detailed document on counteracting the changes was being drafted and would soon be given to provincial authorities.

The Yellow River Delta, totaling 8,000 square kilometers, is the youngest land of China's eastern coastal area. The river is the most silted in the world, and it dumps more than 900 million tons of it to form an alluvial plain before joining the sea.

The delta has claimed 2,708 square kilometers of land since the river's last major course change in 1855, shaping a unique wetland landscape.